Not everyone is sold on the benefits of Face ID, the facial-recognition system Apple unveiled Tuesday as a convenient biometric method for unlocking devices.

Introduced along with the iPhone X, the system uses the phone's front-facing camera to scan and register your facial structure for use as a password, eliminating the need to input a keypad password or scan a fingerprint. Using facial recognition to unlock a device isn't a new concept, and previous attempts have shown the technology can easily be tricked.

Now playing:Watch this:
Apple explains Face ID on iPhone X

2:35

Device security, however, doesn't appear to be former NSA contractor Edward Snowden's major concern. He's more worried about privacy, a topic he's advocated for since fleeing the US in 2013 after leaking classified documents about the agency's secretive surveillance tools.

Like many in the tech community, Snowden turned his attention to Apple's Face ID, tweeting a generally positive review of the biometric security system. He was impressed by what he called a "surprisingly robust" design. Still, he tempered the praise by noting that normalizing facial scanning could make it ripe for abuse.

Facial recognition used as part of government surveillance efforts has long been a concern of privacy advocates. While the technology could be used to identify suspected terrorists, the American Civil Liberties Union worries that systems used for surveillance purposes could become increasingly invasive over time.

"Once installed, this kind of a surveillance system rarely remains confined to its original purpose," the ACLU wrote in a Q&A on the subject. "New ways of using it suggest themselves, the authorities or operators find them to be an irresistible expansion of their power, and citizens' privacy suffers another blow. Ultimately, the threat is that widespread surveillance will change the character, feel, and quality of American life."

Apple's Face ID follows Samsung's use of a similar feature in the Galaxy Note 7. Microsoft also used facial recognition as a password on Windows 10 devices.